Radiotelegraphic plant.



E.- GIRARDEAU.

RADIOIELEGRAPHIC PLANT.

APPLICATION FILED DEC. 1, 19H.

Patented Aug. 24, 1915.

UNITED STATES PATENT OFFICE.

EMILE GIIBARDEAU, OF PARIS, FRANCE, ASSIGNOR OF ONE-HALF TO JOSEPHIBETHENOD,

' OF PARIS, FRANCE.

- RADIOTELEGRAPHIC PLANT.

To allwlm'm it may concern Be it known that I, EMILE GIRARDEAU,engineer, a citizen of the Republic of France, residing at Paris, in theRepublic of France, have invented certain new and useful Improvements inRadiotelegraphic Plants, for which application has been'made in FranceDecember 1, 1910.

A receiver for radiotelegraphic plants ought to possess theoreticallythe following properties, viz

1. It ought to be adapted to be-tuned for waves of various lengths whilepreserving always the, same sensitiveness whichever may be the length ofthe wave.

2. It ought to permit the maximum of syntony after the tuning with thecorresponding station has been once effected to be obtained.

3. It ought to comprise as few regulating devices as possible.

4. It ought to require as little space as possible.

Practically the simultaneous realization of all these conditionspresents great ditficulties owing to the fact that, in order to attain asufficient syntony, an induction jigger with separate windings has to beused,

although this jigger oflers certainly from a good many points of viewmuch greater complications than the jigger with simple winding used forshunting. However it is evident, that the construction of a singlej1gger is much simpler than the construc- .tion of two, one of whichthen must be provided with a device permitting the changing of theirrelative positions.

This invention relates to a new receiver which particularly offers inthe most complete form all the properties hereinbefore enumerated. Thisimproved apparatus is based upon the following principles: In a normalreceiver post with induction jigger, this jiggcr, considered by itself,constitutes a converter without iron having a determined dispersioncoeiiicient c. On the other hand if X designates the ratio of thecoefficient of the apparent self-induction of the antenna with regard tothe coefiicient of self-induction of the primary winding of the jigger,it is clear that the coefficient of the real coupling between the twocircuits,

Specification of Letters Patent.

Patented Aug. 24, 1915.

Application filed. December 1, 1911. Serial No. 663,360.

the primary and the secondary of the recelver system, is equal tot =x/as 9 1+1 This equation is the result ofthe follow- 1ng development: Ifthe respective coeflicients of self-induction of one of the n prithatthe total primary self-induction is l -l-nl and the total secondaryinduction is M The total mutual induction is measured by n m and thefollowing equation may be written out in accord with the well knowndefinitions used in the theoretical study of high frequency currents:

In order to adapt the apparatus to the various lengths of waves between0 and a maximum, the coupling coefiicient must be varied between zeroand the maximum;

and finally it therefore is necessary to act upon according to theformula hereinbefore stated; this is however not very rational.According to this invention this inconvenience 1s avoided by subsitutingfor the single jigger,

generally used, a certain number of pggers, the primary and secondarywindings of which are respectively connected in series; according to thewave length of the sender station the number of such jiggers is variedby means of a suitable connnutator and in applying the formula as aboveone can easily verify whether the coupling coeiticient remains constantwhichever may be the number of jiggers coupled for a given number of x.

In the accompanying drawings a diagram of connections and a couplingapparatus for the jigger is shown by way of example.

Figure 1 shows the apparatus with four jiggers. Fig. 2 illustrates amodified construction permitting of the easy and simultaneous regulationof all the jiggers in very wide limits.

In Fig. 1, the antenna A is connected with the primaries P P P P of thejiggers in question through the intermediary of the self-inductance S,the ground contact T being insured by a conductor'in which the condenserC is inserted. The secondaries S S 8,, S, are mounted as well as theprimaries in series in the circuit of the detector D.

By means of the commutators M, M it.

is evidently possible to vary the number of jiggers actually in use,according to the length of wave from the sender station, saidcommutators M, M being adapted to be connected with each other in such amanner that the one participates in the movements of the other. Thus, asshown in Fig. 1, the commutators M, M canbe mounted upon an insulatedregulator handle 0 allowing their simultaneous operation, so that thecommutator M rests uponthe contact 1 when the commutator M rests uponcontact 1' and the commutator M rests upon contact 2 when the commutatorM rests upon contact 2', etc. It is obvious that there can be providedany number n) of jiggers. As regards the coupling coetlicient p it canbe modified at will it' one acts upon 6, that is to say by changing therelative position of the primaries and of the secondaries.

According to Fig. 2 the (n) primary windings are wound around bobbins Pwhich are shown in section; these (n) bobbins are arranged -in a circlearound the axis X, X and they are fixed in a frame B. The (n) secondarybobbins S are mounted upon a frame B". The coupling ot' the bobbins canbe varied within very wide limits if one of the frames is made to turnaround the axis X, X so that the coetlicient p can exactly attain thevalue zero. This angular displacement can be replaced by or combinedwith a movement of translation of one of the frames along the axis X, X;in this case the diameters of the primary and secondary bobbins will bechosen of different width so as to permit of the bobbins beingtelescoped one into the other at the end of the movement of translation.The platform B which supports the primaries P is provided with a socketI, which forms a threaded guide for the screw V which can be turned bymeans of a rifled knob (lr. A key ll extending through a fork J carriedby the socket I prevents the rotation of the platform l3, andconsequently compels the same to execute a vertical movement upon therotation of the screw V. However. as soon as the platform I) arrives atthe end of its path it will abut against the shoulder l, and ll is atthis moment disengaged from the fork J and the platform 13 turns in a.horizontal plane.

The form of execution of the principle of invention hereinbet'oredescribed evidently possesses the PI'OIXltlQS mentioned under numbers 1,3 and 4.

There is further obtained a very pronounced syntony owing to the greatfacility with which the coupling can be modified. In the cases where thesynton'y ought to be pushed to the extreme there can easily beestablished an intermediary circuit by the adjunction ot' a simpleinterrupter. It the interrupter is placed at I (Fig. 1) a loop will beformed it' the said interrupter is closed, said loop being composed ofthe selfinductance S, of the primaries P. P,,, I,

and of condenser C. This loop constitutes an intermediary circuitoscillating between the system of the ground antenna and the series ofjiggers. the coupling with the said system being besides easy toregulate by displacing for example the contact It.

Having now particularly described and ascertained the nature of my saidinvention, and in what manner the same is to be performed, I declarethat what I claim is:

1. Receiver for radio-telegraphic stations comprising an antenna, aplurality of induction-jiggers having their primaries, consisting ofcoils separated to such a distance that they have no influence upon eachother, arranged in series with each other and their secondaries inseries with each other, and means for switching into circuit a greateror smaller number of induction jiggers according to the waves receivedfrom the sender station. 1

Receiver for radio-telegraphic stations comprising a plurality ofinduction-jiggers, a displaceable frame upon which the primaries of saidinduction-jiggers are mounted, means for displacing said frame forvarying the relative position of the primaries with respect to thesecondaries, and means for mechanically coupling the primary andsecondary of the transformer so that the number of coils in each can bevaried uniformly and simultaneously.

3. In a receiver for radio-telegraphic stations comprising an antenna, aplurality of jiggers having their primaries and their secondariesarranged in series, a self-inductance apart of which connects theprimaries of said jiggers with said antenna, a condenser between saidjiggers and the ground, and means for grounding a point of theselfinductance for establishing an intermediary circuit comprisingself-inductance of the primary jigger windings and said condenser,substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

EMILE GIRARDEAU.

Witnesses:

J. BETHENQD, BARTLEY F. Yos'r.

